Sudden cardiac arrest risk factors: who is more likely

What sudden cardiac arrest is

In cardiac arrest the heart suddenly stops pumping, so blood stops flowing to the brain and other vital organs. It is caused by certain types of arrhythmias (irregular heart rhythms) that keep the heart from pumping blood. It is a medical emergency: NHLBI says nine out of 10 people who have a cardiac arrest outside of a hospital die, often within minutes (NHLBI).

A person may be having a cardiac arrest if they collapse suddenly and pass out, are not breathing or are only gasping, do not respond to shouting or shaking, and do not have a pulse (NHLBI).

Cardiac arrest is not the same as a heart attack

A cardiac arrest is caused by an electrical problem in the heart that stops the heartbeat. A heart attack is caused by a blocked artery in the heart: the loss of blood flow damages the heart muscle, but the heart usually keeps beating (NHLBI). MedlinePlus notes that a cardiac arrest can sometimes happen after or during recovery from a heart attack (MedlinePlus).

What causes it

Arrhythmias cause cardiac arrest. The main cause is ventricular fibrillation or ventricular tachycardia (NHLBI). In ventricular fibrillation, the heart's lower chambers beat very fast and very irregularly and cannot pump blood to the body; MedlinePlus says this causes most sudden cardiac arrests (MedlinePlus). In children, cardiac arrest can follow respiratory arrest (breathing has stopped) from choking or drowning. Sometimes the cause is not known (NHLBI).

Who is more likely to have one

NHLBI says heart problems are the most important risk factors (NHLBI):

• Coronary heart disease. Most people who had a cardiac arrest outside of a hospital had heart disease, although they may not have known it. Complications of coronary heart disease, such as heart attack, angina and coronary artery spasm, also count. See heart disease risk factors.
• Arrhythmias, including atrial fibrillation and long QT syndrome.
• Problems with the heart's structure: congenital heart defects (present at birth), cardiomyopathy and heart valve disease.
• Heart inflammation caused by an infection or a medical condition (see myocarditis risk factors).
• Heart failure, whose complications can include cardiac arrest.

Other risk factors NHLBI lists (NHLBI):

• Age. Risk increases with age, and cardiac arrest is rare in people younger than 30. In younger people the main risk factors are genetic arrhythmias, problems with the structure of the heart or coronary arteries, heart inflammation and substance use. In older adults they are coronary heart disease and other heart conditions.
• Sex. Most cardiac arrests occur in men. Women's risk increases after menopause.
• Race and ethnicity. Black people have double the risk of dying from cardiac arrest that white people have, and Black women's risk is higher than Black men's. Hispanic and Asian people may have lower risk than white people. NHLBI says heart disease risk factors such as high blood pressure and diabetes partly explain the higher rate in Black people, and its ARIC study suggests that social factors (lower income and education levels) are even more important.
• Family history. Some conditions that raise the risk run in families. Genetic disorders are the main cause of cardiac arrest in children and young adults. Tell your provider about blood relatives who have arrhythmias or cardiac conduction disorders, had a cardiac arrest, or died early, unexpectedly or of unexplained causes, including sudden infant death syndrome (SIDS).
• A past cardiac arrest. If you had one, your risk of another is very high: one in 5 survivors will have another life-threatening arrhythmia within the next year.
• Other medical conditions and events: respiratory arrest (from choking, drowning, trauma, drug overdose, poisoning, or conditions such as pneumonia and seizure disorders); diabetes; changes in blood levels of potassium, magnesium and calcium; some antibiotics, diuretics and heart medicines that can worsen arrhythmias; and a hard blow to the left side of the chest, directly over the heart, most often from a baseball, hockey puck, softball or lacrosse ball. Children, mainly boys, are at highest risk of this chest injury.

MedlinePlus gives a similar list and adds that Black or African American people are at higher risk especially if they also have conditions such as diabetes, high blood pressure, heart failure or chronic kidney disease, and that a problem with drug or alcohol use raises the risk (MedlinePlus). Neither source gives a score. NHLBI notes that half of cardiac arrests happen to people who did not know they had a heart problem (NHLBI).

What can trigger one

Triggers are more common in people who have heart conditions or other risk factors. NHLBI lists (NHLBI):

• Heavy alcohol use or binge drinking
• Physical exertion or physical stress, including competitive sports. Regular physical activity, however, lowers the risk.
• Recent use of cocaine, amphetamines or marijuana
• Too much coffee, more often in people who do not usually drink it, or too much caffeine from powders, pills or energy drinks
• Severe emotional stress in the prior month
• Flu (influenza) infection in the prior month

Vigorous activity in people, especially men, who do not exercise regularly, and alcohol misuse are the triggers most often linked with cardiac arrest: about 2 in 20 cardiac arrests are linked with physical exertion and up to 3 in 20 with alcohol (NHLBI).

Warning signs

Most people who had a cardiac arrest had one or more symptoms in the hour before, and some symptoms may appear a few weeks before. But many people have no symptoms first. NHLBI lists possible warning signs of a heart attack, a key cause of cardiac arrest: shortness of breath, unusual tiredness, back pain, flu-like symptoms, belly pain, nausea and vomiting, chest pain, repeated dizziness or fainting (especially while exercising hard, sitting or lying on your back) and heart palpitations (NHLBI).

Call your provider if you have warning signs such as fainting or chest pain. NHLBI says people who get medical care for warning signs are 5 times more likely to survive cardiac arrest (NHLBI).

Can it be prevented?

Coronary heart disease is the main risk factor for cardiac arrest in adults. NHLBI says heart-healthy living throughout life, such as never smoking, eating healthy and being physically active, can prevent coronary heart disease and its complications (NHLBI). MedlinePlus adds that treating coronary artery disease or another heart disease can lower the risk, and that an implantable cardioverter defibrillator (ICD) can lower the chance of another arrest in people who have had one (MedlinePlus).

To see your own long-term heart risk, try the heart risk calculator (PREVENT).

Common questions

Is sudden cardiac arrest the same as a heart attack?

No. Cardiac arrest is an electrical problem that stops the heartbeat; a heart attack is a blocked artery, and the heart usually keeps beating (NHLBI).

Who is most at risk?

People with heart problems, above all coronary heart disease, are most at risk. Risk also rises with age, and most cardiac arrests occur in men (NHLBI).

Can young, healthy people have a cardiac arrest?

It is rare under 30. In younger people the main risk factors are genetic arrhythmias, structural heart problems, heart inflammation and substance use (NHLBI).